This invention relates to digitizing systems for inputting positional data to a computer or the like and, more particularly, in a hand-operated digitizing system wherein a cursor is hand-positioned at points to be digitized on a line contained in a drawing disposed on a tablet surface and the position of the cursor is determined by a sensed interaction between the cursor and the tablet, to the improvement to allow easier positioning of the cursor at the points to be digitized comprising, a quasi-sight window in the cursor comprising, sensing means for viewing a 2-dimensional area and developing an electrical signal output reflecting the contents of the 2-dimensional area, and display means connected to receive the electrical signal output for displaying the contents of the 2-dimensional area; a positional line disposed across the display means; positional signal generation means disposed in the cursor for continuously generating and outputting positional data from which a reference point position and the orientation of the positional line on the tablet surface can be dynamically determined; and, position determination logic means for inputting the electrical signal output from the sensing means and the positional data from the positional signal generation means and for determining a point on the tablet surface where the positional line crosses a line contained in a drawing disposed on the tablet surface over which the quasi-sight window is positioned as a point to digitize.
Digitizing systems for inputting positional data to a computer are well known and used in the art. Basically, prior art digitizers fall into two broad groups--automated digitizers and hand digitizers. Automated digitizers are quite expensive and, therefore, not as widely used as hand digitizers. In an automated digitizer, the vectors comprising the material to be digitized are scanned by an optical scanner in substantially the same way as a facsimile machine scans a document to be transmitted. In a hand digitizing system, a document 10 having vector data such as the curve 12 to be digitized is temporarily attached to the surface of a digitizing tablet 14. An operator then moves a cursor 16 over the curve 12 by hand while keeping the cross-hairs 18 of a transparent sight window 20 on the curve 12. At each point on the curve 12 where data is to be output, one of the buttons 22 is pushed to generate a read signal which is recognized by the computer (not shown) attached thereto. The position of the cursor 16 (and in particular the position of the cross-hairs 18) is sensed by an interaction between the tablet 14 and the cursor 16. Various techniques are employed for this sensing, which are not necessary to an understanding of the need for the present invention. It is only important to note that there is a sensing interaction between the cursor 16 and the tablet 14. It is important to note, however, that a small job of digitizing with such prior art equipment is easily accomplished; but, larger jobs become tedious very quickly if they are to be done with any degree of accuracy. The user must be constantly vigilant to keep the cross-hairs on the curve 12, for example. This results in a high degree of stress and a high intensity environment for the use of the equipment.
Wherefore, it is an object of this invention to provide a hand digitizing system in which digitizing of data through line following techniques can be accomplished in a low stress environment.
It is another object of this invention to provide a hand digitizing system in which digitizing of data through line following techniques can be accomplished in a semi-automated manner.
Other objects and benefits of the invention will become apparent from the detailed description which follows hereinafter when taken in conjunction with the drawing figures which accompany it.